Traction trocar apparatus and method

ABSTRACT

The trocar system includes a cannula insertable through a body wall using an obturator having a distal tip. A traction tread disposed interiorly of the obturator inverts at the distal tip and extends proximally along the outer surface of the obturator or cannula. At the distal tip the tread can facilitate parting rather than cutting the tissue. Along the outer surface, the tread can engage the tissue to pull it proximally along the advancing obturator. This produces counter forces which can result in a net proximal force facilitating distention of the abdominal wall and separation of the abdominal wall from internal organs. The traction tread can be axially and/or radially continuous. An associated method of operation includes the steps of contacting the body wall with the traction tread at the distal tip, and engaging the body wall with the traction tread along wall portions facing the outer surface.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates generally to trocar systems and more specificallyto obturator apparatus and methods for placing a trocar cannula across abody wall.

2. Discussion of the Prior Art and Related Technology

It is generally well known that holes can be created through body tissueeither by cutting the tissue or by mechanically parting the tissue alonglines of weakness. Where tissue is cut, it is severed along a line,which is determined by the direction of the cutting implement. Wheretissue is parted, it separates along natural tissue planes such as thosedefined by muscle fibers or differing layers of tissue such as skin andmuscle. Tissue that is mechanically separated tends to heal better thantissue that is cut with tissue that is mechanically separated thehealing process requires only that the affected tissues re-approximateeach other with cut tissue, and in particular muscle fibers, the healingprocess must reconstruct the damaged tissue, often with resultantscaring and incomplete reconstruction. It has been shown forlaparoscopic surgery in particular, that trocar wound sites of 10millimeters in diameter and higher, made by cutting obturators, requiresuturing to prevent incisional hernias from occurring. It has also beenshown that where the same size would site is created by expanding orparting the wound from a cut of 3 millimeters, for example, that thewound site does not require stitching and tends to heal faster.

For laparoscopic surgery there is a requirement that instrument ports inthe form of cannulas be placed in the patient's abdominal wall. Thesecannulas are then used as access ports for the surgeon to placeinstruments such as scissors and graspers. In the past these cannulashave been introduced by using a sharp cutting obturator, placed withinthe cannula, to cut a line or hole for advancing the cannula through theabdominal wall. The obturator is then removed from the cannula and thecannula is left in place for the duration of the surgery.

For most surgeries the cutting obturator is only used after the abdomenhas been insufflated with carbon dioxide gas. There is then separationbetween the abdominal wall and the underlying anatomical structures andorgans. Even with this separation, however, there is a risk that thepatient will be injured by the sharp cutting tip of the obturator as itbreaks through the abdominal wall. To help resolve this issue a varietyof mechanical shielding mechanisms have been employed to cover thecutting element once it breaks through the abdominal wall. It has beennoted and observed that even with these mechanical shield mechanismsthat the risk is not completely eliminated and that the rigid shieldsthemselves can cause damage to internal organs and structures.

Other methods have been used as well. For example, optical trocars havebeen provided with a clear plastic cutting tip. This allows the surgeonto view the tissue layers as they are cut, and in principle to bettercontrol the timing of insertion forces. These plastic tips, however, arenot as sharp as the metal bladed variety and therefore require a higherinsertion force which in turn increase abdominal wall distortion. Thisdistortion or tenting brings the obturator tip into closer proximitywith the internal organs and increases the chances for potential damage.The wound created by such a device is still a cut and not a mechanicalseparation, as it still suffers from the above-mentioned disadvantages.

Another manufacturer employs a multistage system whereby a sheath isinserted over a veress needle. The needle is then removed and a conicalobturator, placed inside a cannula, is inserted through the sheaththereby expanding it to the desired cannula size. The obturator is thenremoved leaving the cannula in place. This offers the advantage of asmaller initial incision with the veress needle. However, the needlestill presents a risk to internal organs, and the system is moreexpensive and complex than those associated with the cutting obturatordevices.

In all of these systems of the past, a cutting element is employed toeither create the final size of the wound site or to make a smallerinitial wound site that is then expanded to the final size. The use ofsharp cutting elements common to all systems presents an unavoidablerisk to the patient.

SUMMARY OF THE INVENTION

These deficiencies of the prior art are overcome with the presentinvention which provides for the parting rather than cutting of tissue,and, the use of opposing radial forces which precede the tip of theobturator shaft. After the tissue is parted, it is drawn proximallyalong the outer surface of the shaft as the shaft is moved distallythrough the body wall. The resulting counter forces can produce a netproximal force on the body wall with a minimal distal or penetrationforce.

In a preferred embodiment a tubular mesh sleeve is initially disposed inthe hollow shaft of the obturator. This sleeve is pulled out of a holeat the tip of the obturator shaft and drawn radially and proximallyalong the outer surface of the shaft. The mesh sleeve inverts at thedistal tip facilitating its movement interiorly of the shaft and itstraction with the parted tissue exteriorly of the shaft.

In one aspect of the invention, an apparatus is provided for creating anopening through body tissue. The apparatus includes a shaft having anaxis and a channel extending axially between a proximal end and a distalend. The shaft has a distal tip and a hole in the tip communicating withthe channel of the shaft. Portions of the tip define a leading surfaceof the tip. Means is disposed along this leading surface and is moveablerelative to the tip for creating generally opposing forces on the bodytissue which tend to part the body tissue and thereby create the openingthrough the body tissue.

In another aspect of the invention, a surgical instrument is used forcreating an opening through an abdominal wall retaining internal organs.The instrument includes a shaft having an outer surface and a tip. Asheath initially contacting the body tissue generally at a point extendsproximally from the point along the outer surface of the shaft. Theshaft is operable to create a distal force on the body tissue while thesheath is operable to create a proximal force on the body tissue. Theproximal force is greater than the distal force in order to create a netproximal force on the abdominal wall tending to separate the abdominalwall from the internal organs as the opening is created.

In another aspect of the invention, a flexible sheath having a tubularconfiguration extends from an axial channel of the shaft through thedistal tip of the shaft. A handle is attached to the sheath exteriorlyof the shaft and is moveable proximally relative to the shaft towithdraw the sheath from the channel and to progressively invert thesheath at the tip of the shaft.

In another aspect of the invention, the shaft of the surgical instrumenthas a tubular configuration with an outer surface, an axial channel, anda distal tip. At least one flexible traction tread is carried within theaxial channel and extends outwardly of the shaft at the distal tip. Ahandle attached to the traction tread exteriorly of the shaft ismoveable proximally to withdraw the traction tread distally through thedistal tip.

An associated method of operation includes even further aspects of theinvention. For example, a method for creating an opening in body tissueincludes the steps of providing opposing traction treads extending fromthe axial channel of the shaft outwardly through the hole in the tip ofthe shaft. The body tissue is contacted with the traction treads at thetip of the shaft and the traction treads are moved radially outwardlyfrom the hole in the tip. During this moving step, the body tissue isengaged at the tip to produce parting forces on the body tissue tendingto separate the body tissue and thereby create the opening through thebody tissue.

In another method of operation, first and second cannulas are insertedthrough body tissue by providing an obturator having a shaft with anouter surface and a traction tread moveable relative to the outersurface. Placing the obturator in the first cannula, the body tissue isengaged with the tread and the tread is moved relative to the outersurface of the shaft to facilitate penetration of the body tissue by theshaft and the first cannula. The obturator is then removed from thefirst cannula and placed in the second cannula where again the tractionthread engages the tissue and facilitates penetration of the body tissueby the shaft in the second cannula. Removing the obturator from thesecond cannula leaves both the first cannula and the second cannulaoperatively disposed across the body wall.

In another method associated with the invention, removal of a trocarcannula from a body wall is facilitated by placing a mesh sleeve betweenthe cannula and the body wall. The sleeve is provided with propertieswhich exert a radial force on the cannula tending to resist removal ofthe cannula from the body wall. However, an axial force can be appliedto the sleeve to reduce the radial force of the sleeve on the cannula.During this step of applying the axial force, the cannula can be removedfrom the body wall.

In a method for inserting an obturator, the obturator is provided with ashaft having an outer surface and a traction tread moveable along theouter surface of the shaft. The tread is carried within the shaft. Asthe obturator is moved through the body wall, a first force is appliedto the obturator in a first direction and a second force is applied tothe obturator in a second generally opposing direction. As the obturatoris moved distally relative to the body wall, it engages wall portionswhich face the outer surface of the shaft and pulls those wall portionsproximally along the shaft.

These and other features and advantages of the invention will be betterunderstood with reference to preferred embodiments of the concept andreference to the associated drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a patient with insufflated abdomenand trocars in the process of being placed using the trocar system ofthe present invention;

FIG. 2 is a side elevation view of a prior art trocar system involvingan incision and blunt tip obturator;

FIG. 3 is a side-elevation view of a prior art trocar system involvingan obturator with cutting wings;

FIG. 4 is a side elevation view of a prior art trocar system including acutting tip;

FIG. 5 is a side elevation view of the system of FIG. 4 invading aninterior organ;

FIG. 6 is a side elevation view of the system of the present inventionincluding an inverting sheath operable with counter forces which canproduce a net proximal force on the body wall;

FIG. 7 is a side elevation view of an embodiment including a singletraction tread;

FIG. 8 is a radial cross section view taken along lines 8—8 of FIG. 7;

FIG. 9 is a side elevation view of an embodiment including a pair ofopposing traction treads;

FIG. 10 is a radial cross section view taken along lines 10—10 of FIG.9;

FIG. 11 is a side elevation view of an embodiment having more than twotraction treads equally circumferentially spaced;

FIG. 12 is a radially cross section view taken along lines 12—12 of FIG.11;

FIG. 13 is a side elevation view wherein the traction tread is radiallycontinuous and forms a tube or traction sheath;

FIG. 14 is an axial cross section view taken along lines 14—14 of FIG.13;

FIG. 15 is an end view taken along lines 15—15 of FIG. 14;

FIG. 16 is a side elevation view of a further embodiment of theobturator wherein opposing traction treads are axially continuous;

FIG. 17 is an axial cross section view taken along line 17—17 of FIG.16;

FIG. 18 is an end view taken along line 18—18 of FIG. 17;

FIG. 19 is a front elevation view similar to FIG. 16 and illustrating anembodiment including axially continuous traction treads;

FIG. 20 is an axial cross section view taken along lines 19—19;

FIG. 21 is an end view taken along lines 21—21 of FIG. 20;

FIG. 22 is a side elevation view of the embodiment of FIG. 13 placed ininitial contact with an abdominal wall to produce opposing partingforces;

FIG. 23 is a side elevation view similar to FIG. 22 and showing theobturator with the abdominal wall being drawn upwardly onto the cannulaof the trocar system;

FIG. 24 is a side elevation view similar to FIG. 23 and illustrating theabdominal wall fully parted by the trocar cannula;

FIG. 25 is a side elevation view of the embodiment illustrated in FIG.24 showing the abdominal wall drawn proximally onto the trocar cannulaby the traction sheath;

FIG. 26 is the side elevation view of the system illustrated in FIG. 25with the traction sheath fully deployed to maintain traction between theabdominal wall and the cannula, and with the obturator removed to vacatethe working channel of the cannula;

FIG. 27 is a side elevation view of the system illustrated in FIG. 26with the trocar cannula removed from the traction sheath;

FIG. 28 is a side elevation view of the system illustrated in FIG. 27showing the traction sheath removed from the opening leaving partedsurfaces to promote healing;

FIGS. 29–32 illustrate a series of side elevation views showingprogressive steps for operating an embodiment wherein the invertingsheath is disposed outwardly of the obturator but inwardly of the trocarcannula;

FIG. 33 is a side elevation view of a blunt-nose obturator havingwindows to facilitate the return of the inverting sheath to an interiorchannel of the obturator;

FIG. 34 is a cross section view taken along lines 34—34 of FIG. 33;

FIG. 35 is a side elevation view similar to FIG. 33 and showing anobturator tip with converging planes;

FIG. 36 is a front elevation view taken along lines 35—35 of FIG. 34;

FIG. 37 is an axial cross section view of an obturator similar to thatof FIG. 34 and including a biasing means for returning the invertingsheath to its initial position;

FIG. 38 is an axial cross section view similar to FIG. 37 andillustrating the biasing means stretched to a final position of theinverting sheath;

FIG. 39 illustrates a fabric adapted for use as a traction tread orsheath, the fabric being illustrated in a normal state;

FIG. 40 is a side elevation view of the mesh of FIG. 39 axiallystretched;

FIG. 41 is a side elevation view of the mesh of FIG. 39 radiallystretched;

FIG. 42 is an end view of the traction-sheath formed of the mesh of FIG.39;

FIG. 43 is an end view similar to FIG. 41 of the inverting sheathforming pleats to provide texture for traction;

FIG. 44 is a side elevation view of a further embodiment of theobturator including a blunt tip with a conical point for microscopicpuncture;

FIG. 45 is an end view taken along lines 45—45 of FIG. 44;

FIG. 46 is a perspective view of an application adapted for use inplacing the trocar system of the present invention;

FIG. 47 is a schematic axial cross section view of a further embodimentincluding gears with circumferential teeth;

FIG. 48 is an end view of the embodiment illustrated in FIG. 47;

FIG. 49 is a schematic axial cross section view of a further embodimentincluding a single oscillating gear; and

FIG. 50 is an end view of the embodiment of FIG. 49.

DESCRIPTION OF PREFERRED EMBODIMENTS AND BEST MODE OF THE INVENTION

A trocar system of the present invention is illustrated generally inFIG. 1 and designated by the reference numeral 10. The system 10includes a trocar cannula 12 having a seal housing 14, and an obturator16 with a shaft 18 and handle 21, and including a traction mechanism 23of particular interest to the present invention. The obturator 16 isused in placing the cannula 12 across a body wall such as an abdominalwall 25, associated with a patient 27. In the case of the abdomen, thewall 25 defines an abdominal cavity 29 which includes many organs suchas that designated by the reference numeral 30.

In less evasive laparoscopic procedures, multiple cannulas 32 and 34 areused to provide access across the abdominal wall 25 to facilitatesurgical procedures within the abdominal cavity 29. By way of example,the removal of a gallbladder is typically accomplished with such alaparoscopic procedure. Initially, cannulas 12, 32 and 34 are placedacross the abdominal wall 25, each providing a working channel throughwhich various instruments can be inserted and surgically manipulated.For example, the cannula 32 is shown with a grasper 36 which can beinserted through the cannula to grasp the organs 30 or other tissuewithin the abdominal cavity 29. A fiber-optic scope 38 is illustrated inFIG. 1 operatively disposed through the cannula 34 and across theabdominal wall 25 to provide visualization within the abdominal cavity29.

As further back-ground to the trocar system 10 of the present invention,FIGS. 2–5 are provided and to illustrate the deficiencies of trocars andobturators of the prior art.

One trocar of the prior art is illustrated in FIG. 2 and is designatedby the reference numeral 41. This trocar includes a cannula 43 and bluntobturator 45. In the placement of this device, an incision 47 is cutentirely through the abdominal wall 25 using a scalpel 50. All of thedeficiencies previously discussed with respect to cutting rather thanparting the abdominal wall 25 impact this procedure. After the incision47 is cut, the blunt obturator 45 is moved through the incision to placethe cannula 43 across the wall 45. Due to the delicate cutting requiredby this procedure, placement of this trocar 41 may take as long as 10minutes. In a procedure requiring the placement of four trocars, thistime intensive procedure would require as much as 40 minutes, forexample.

In comparison, placement of a self-cutting obturator may require onlyone minute of time. In a procedure requiring the placement of fourtrocars, this part of the procedure may require only four minutes oftime as opposed to the 40 minutes of time required for the precutprocedure of FIG. 2.

A self-cutting trocar system 52 of the prior art is illustrated in FIG.3. This system 52 includes a cannula 54 and an obturator 56 having apair of opposing wings 58. These wings 58 are provided with sharpenedouter edges so that they tend to cut a path through the abdominal wall25. Again, the disadvantage of cutting an incision through the abdominalwall 25 also impacts this embodiment.

Perhaps the most widely used embodiment of a trocar is that illustratedin FIGS. 4 and 5. In this case, a trocar 61 includes a cannula 63 andobturator 65 having a sharpened point 67. A safety shield 70 associatedwith the obturator 65 is biased to move over the point 67 and to protectthe interior organs 30 upon penetration of the abdominal wall 25. In theprocess associated with this instrument, the trocar 61 is forced throughthe abdominal wall 25 creating a significant distal force on the wall25. This distal force provides the wall 25 with a concave shape,commonly referred to as tenting, and tends to bring the point 67 intoclose proximity to the interior organs 30.

As with the prior art embodiment of FIG. 3, the point 67 precedes theremainder of the trocar 61 as it cuts the tissue of the wall 25.Therefore, of the deficiencies previously discussed with reference tocutting are applicable to this prior art embodiment. Furthermore, thesignificant force required for penetration, a force typically as high asten pounds, coupled with close proximity of the concave wall 25 to theorgans 30, tends to provide little time for the safety shield 70 tocover the tip 67. As a consequence, damage to the interior organs 30 hasbeen severe notwithstanding the presence of the safety shield 70.

The high forces required for penetration are particularly applicable tothose trocar systems which require both penetration forces as well ascutting forces.

In all of these embodiments of the prior art, it will be noted thatcutting of the abdominal wall is required. Furthermore, all forcesassociated with movement of the trocars 41, 52 and 61 through theabdominal wall 25 produce a distal force as great as ten pounds whichtends to move the abdominal wall 25 into a concave shape and into closeproximity with the interior organs 30.

The advantages of the trocar system 10 of the present invention will bereadily apparent with reference to the obturator 16 of FIG. 6 and acomparison with the prior art devices illustrated in FIGS. 2–5. Aspreviously discussed, this obturator 16 includes the shaft 18, handle 21and traction mechanism 23. In this case, the traction mechanism 23 mayinclude a fabric 72 having the configuration of a tube with a first end74 and a second end 76. In this context, the word “fabric” refers to anyflexible sheet material. The shaft 18 can be solid, but in a preferredembodiment it is at least partially hollow to receive the first end 74of the fabric 72 within the shaft 18. The shaft 18 extends to a distaltip 78 having a wall 81 that defines an internal channel 83 and an axialhole 85. This wall 81 is defined by a leading surface 87.

The tubular fabric 72 is initially disposed with its first end 74positioned in the interior channel 83. The fabric 72 extends distallyoutwardly through the hole 85 where it inverts and extends proximallyalong the leading surface 87 and the outer surface 90 of the shaft 18.At the second end 76, the tubular mesh is preferably attached to afinger engagement means, such as a projection, tab, flange or ring 92.

In operation, the handle 21 of the obturator 16 is placed in the palm ofthe user's hand and his/her fingers are extended to engage the ring 92.In a common and familiar motion, the hand of the user is closed drawingthe fingers towards the palm of the hand. This moves the ring 92 towardthe handle 21 and draws the tubular fabric 72 distally through the hole85 and proximally along the outer surface 90 of the shaft 18. As thering 92 moves proximally upwardly in FIG. 6, the first end 74 of thefabric 72 is pulled toward the distal tip 78 where the fabric 72 exitsthe hole 85 and inverts to move along the outer surface 90. With thefabric 72 disposed between the shaft 18 and the abdominal wall 25, ittends to grip the abdominal wall 25, and move the wall 25 proximallyalong the shaft 18. As the wall 25 moves upwardly in FIG. 6 along theshaft 18, it tends to part at the leading edge 87 along a line ofweakness designated generally by the reference numeral 94. It is ofparticular importance to note that the wall 25 is parted rather than cutin order to achieve the advantages previously discussed. In thisparticular embodiment, there is no structure which works to cut theabdominal wall 25 or otherwise force the obturator 16 along apredetermined path. Rather, the obturator 16 finds its own path alongthe line of weakness 94.

Notwithstanding this significant aspect of the present invention,perhaps the greatest advantage is achieved with a net zero or evenproximal force on the wall 25. As previously noted, the prior artproduced only a distally directed force in creating an incision whilemoving an obturator through the abdominal wall. This tended to move theabdominal wall toward a concave shape and into proximity with theinternal organs. With the present embodiment, the handle 21 can be heldstationary with a distally directed force, shown by an arrow 96, while acounter proximal force of equal or greater magnitude is applied to thering 92, as shown by the arrows 98.

Since these forces, shown by the arrows 96 and 98, are applied indifferent directions, they tend to offset each other so that the netdistal force applied to the abdominal wall 25 can actually be negative.Note for example, that if the handle 21 is maintained stationary, andthe ring 92 is moved upwardly, the net force on the abdominal wall 25 isa proximal-force directed upwardly in FIG. 6. As a result, the abdominalwall 25 can be moved toward a convex shape and a spaced relationshipwith the interior organs 30.

It will be appreciated from the foregoing discussion, that the counterforces which are of particular advantage to the present invention can beproduced from a variety of structures. More specifically, the tubularfabric 72 discussed with reference to FIG. 6 can be any material capableof being pulled along the outer surface 90 of the shaft 18. Thismaterial could be organic or inorganic and will generally be elongate sothat it can be pulled with some magnitude of force in the axial,proximal direction. For example, the tubular fabric 72 of FIG. 6,although preferred for that embodiment, could be replaced with just asingle traction tread 101 as illustrated in FIG. 7. With this tractiontread 101 disposed between the shaft 18 and the abdominal wall 25, thetraction tread 101 will engage the tissue of the abdominal wall 25 andpull it proximally relative to the shaft 18.

Forces will be more balanced if at least two traction treads, such asthe tread 101 and a second tread 103, were diametrically opposed asillustrated in FIG. 9 and 10. With this configuration, the abdominalwall 25 (FIG. 1) is engaged on both sides of the shaft 18 and pulledproximally relative to the shaft 18.

Other embodiments of the invention might include three traction treads,such as the treads 101 and 103 and a third tread 105, equally spacedaround the circumference of the shaft 18. Such an embodiment isillustrated in FIGS. 11 and 12.

While independent and discrete traction treads, such as the treads 101,103 and 105, will function to produce the discrete counter forces, asingle traction tread that is radially continuous, as illustrated inFIGS. 13–15, may be preferred as it provides complete isolation of theshaft 18 from the abdominal wall 25 (FIG. 1). Where the shaft 18 of theobturator 16 is cylindrical and the distal tip 78 is conical or convexas it as illustrated in FIG. 13, this tubular configuration for thetraction tread 107 is particularly desirable. With this configuration,the traction tread 107 passes through the axial hole 85 where it invertsand travels radially as shown by arrows 110 in FIG. 15. Form this point,the traction tread 107 travels proximally along the surface 90 of theshaft 18, upwardly in FIG. 14.

In a further embodiment of the invention, the distal tip 78 of theobturator 16 is formed as a pair of planar surfaces 112 and 114 whichconverts distally in the nature of a flathead screwdriver. Thisconfiguration lends itself to the opposing pair of tractor treads 101and 103 previously illustrated in FIGS. 9 and 10. With thisconstruction, the traction treads 101 and 103 separate generally at anexit slot 116 best shown in FIG. 18. In this view the opposing forcesare shown by the arrows 118 and 121 which produce the tissue partingresults of particular advantage to the present invention.

With reference to FIGS. 19, 20 and 21, it can be seen that a similarembodiment including the converging surfaces 112 and 114 can beaccommodated with traction treads 101 and 103 which are axiallycontinuous. Thus, each of these treads 101 and 103 forms a continuousband 123 and 125 respectively. The two bands 123, 125 counter rotatethrough the slot 116, and extend proximally along the surface 90,returning to the interior channel 83 through opposing windows 127 and130 in the wall 81 of the obturator.

With respect to the embodiment of FIG. 6, the method of operation willnow be discussed with reference to FIGS. 22–28. In these views, theabdominal wall 25 is further defined by a fascia 141, muscle tissue 143,and a peritoneum 145. In this case, the shaft 18 and fabric 72 of theobturator 16 can be inserted through the seal housing 14 and into thecannula 12. A distal end 132 of the cannula 12 is disposed through thering 92 and into the associated tubular fabric 72. In operation, thetrocar system 10 functions by pulling the ring 92 proximally along anouter surface 149 of the cannula 12, upwardly in FIG. 22.

In an initial step of the process, a cut 152 can be made in the skin orfascia 141. This cut 152 is preferably made to gain access to the muscletissue 143 which is more easily parted. The cut 152 also marks thedesired location for insertion of the trocar system 10. As the ring 92is drawn upwardly along the cannula 12, the tubular fabric 72 exits thedistal hole 85, inverts and follows the ring 92 upwardly along the outersurface 149. At the leading surface 187, the inverting fabric 72produces opposing radial forces shown by arrows 154. With these opposingforces, the tissue 143 is parted along the line of weakness 94 (FIG. 6)as the trocar system 10 is moved relatively into the abdominal wall 25.It will be noted that the arrows 154 are merely representative of all ofthe radial forces which emanate from the hole 85 as shown by the arrows110 in FIG. 15.

With reference to FIG. 23, it can be seen that the ring 92 and invertedtubular fabric 72 are preferably drawn proximally by the arrows 98 whilethe cannula 12 and obturator 16 are held stationary as shown by a pairof arrows 156. This produces the counter forces previously described andelevates the abdominal wall 25 as it is pulled proximally upwardly alongthe cannula 12 by the fabric 72.

Full penetration of the abdominal wall 25 including the peritoneum 145is illustrated in FIG. 24. It is interesting to suspend furtherdescription at this point and note that on the distal side of theabdominal wall 25, the trocar system 10 presents no sharp objects thatmight be detrimental to the interior organs 30. There is no scalpel(FIG. 2), no sharp wings 56 (FIG. 3), and no sharp cutting point 67(FIG. 5) characteristic of this prior art. Furthermore, the spacebetween the abdominal wall 25 and the interior organs 30 is actuallyincreased by the net proximal force associated with operation of thetrocar system 10. This space can be even further increased asillustrated in FIG. 25 by merely pulling on the trocar system 10 tofurther elevate the convex abdominal wall 25 into a more conicalconfiguration.

Once the trocar system 10 has fully penetrated the abdominal wall 25,the ring 92 can be drawn further upwardly along the cannula 12 intocontact with the seal housing 14. In a preferred embodiment, thisdisposition of the ring 92 will cause the first end 74 of the tubularfabric 72 to exit the axial hole 85 of the shaft 18 (FIG. 25). At thispoint, the obturator 16 can be removed, leaving the seal housing 14,associated cannula 12 and tubular fabric 72. With the obturator 16removed, the interior working channel of the cannula 12 is vacated tofacilitate access with surgical instruments, such as the endoscope 38and grasper 36 illustrated in FIG. 1.

Even during this stage of the process, the trocar system 10 of thepresent invention offers significant advantages. Noteworthy in thisembodiment is the fact that the tubular fabric 72 remains between thecannula 12 and the abdominal wall 25 even after the obturator 16 isremoved. In this position, the high traction characteristics whichfacilitated penetration of the abdominal wall 25 by the trocar system10, remains to ensure that the cannula 12 stays in place during theinsertion and removal of surgical instruments. The structure that aidedin penetration of the abdominal wall 25 now aids in maintaining thecannula 12 in its preferred operative disposition.

When the surgical operation is complete, the cannula 12 and associatedvalve housing 14 (FIG. 26) can be removed, from the ring 92 and attachedtubular fabric 72. This removal of the cannula 12 may be inhibited in anembodiment wherein the tubular fabric 72 is automatically biased to areduced profile. This bias tends to exert radial forces on the cannulaincreasing the amount of friction which must be overcome to separate thecannula 12 from the tubular fabric 72. In such an embodiment, it hasbeen found that application of an axial force on the ring 92 andattached tubular fabric 72, will tend to radially expand the fabric 72.In FIG. 26, this axial force is represented by an arrow 160. With thisradial expansion of the fabric 72, the-cannula 12 and associated valvehousing 14 can be removed from the tubular fabric 72.

Without the large cannula 12 radially stretching the fabric 72, thetubular configuration will automatically be drawn down to a reduceddiameter as illustrated in FIG. 27. This lower profile greatlyfacilitates removal of the tubular fabric 72 as illustrated in FIG. 28by an arrow 161. It will be noted that once the tubular fabric 72 iswithdrawn, the abdominal wall 25 is left with the parted line ofweakness 94 initially discussed with reference to FIG. 6.

An additional embodiment of the invention is illustrated in theprogressive views of FIGS. 29–32, wherein elements of structure similarto those previously discussed are designated with the same referencenumeral followed by the lower case letter “a.” Thus the trocar system 10a is shown with the cannula 12 a and associated seal housing 14 a. Theobturator 16 a includes the shaft 18 a and handle 21 a, as well as theaxial hole 85 a. The tubular fabric is designated with a referencenumeral 72 a. Note that in this embodiment the tubular fabric 72 a alsoextends through the valve housing 14 a to the ring 92 a which isdisposed proximally of the valve housing 14 a.

This embodiment differs from that previously disclosed in that theobturator 16 a and tubular fabric 72 a are disposed entirely within theworking channel of the cannula 12 a. Thus, the obturator 16 a withfabric 72 a is inserted into the cannula 12 a in the initial step ofoperation. It will be noted that with this construction, the fabric 72 ais exposed to the abdominal wall 25 (FIG. 1) only in a distal region 163where the obturator shaft 19 a is exposed distally of the end 132 a ofthe cannula 12 a. Since this region produces the parting forcesrepresented by the arrows 154 in FIG. 22, as well as the proximalcounter forces, represented by the arrows 98 in FIG. 6, this embodimentprovides many of the advantages previously discussed.

In operation, the obturator 16 a with tubular fabric 72 a is disposed inthe cannula 12 a. The leading edge 87 a is brought into contact with thebody wall 25 a and the ring 92 a is drawn proximally toward the handle21 a as illustrated in FIG. 30. As the tubular mesh emanates from theaxial hole 85 a it inverts in the manner previously discussed pullingthe abdominal wall 25 a upwardly onto the cannula 12 a. The ring 92 a isdrawn proximally into an abutting relationship with the handle 21 a asillustrated in FIG. 31. At this point, the cannula 12 a should be fullyinserted through the abdominal wall 25 a. Following this step in thesurgical procedure, the obturator 16 a as well as the tubular fabric 72a can be entirely withdrawn leaving the cannula 12 a operativelydisposed across the abdominal wall 25 a as illustrated in FIG. 32.

One of the significant advantages associated with this embodiment isthat the obturator 16 a and tubular fabric 72 a can be repeatedly usedin the placement of multiple cannulas, such as the cannula 12 a. Thus, afirst cannula can be placed through the abdominal wall using theobturator 16 a. Upon removal of the obturator 16 a, the first cannulacan be left in place as illustrated in FIG. 32. Then the obturator 16 acan be inserted into a second cannula to facilitate its placement acrossthe abdominal wall. The same obturator 16 a can then be removed tofacilitate placement of additional cannulas.

A further embodiment of the invention is illustrated in FIGS. 33–35where elements of structure similar to those previously discussed aredesignated with the same reference numeral followed by the lower caseletter “b.” This embodiment is similar to that discussed with referenceto FIG. 29 in that the obturator 16 b and tubular fabric 72 b are formedas a subassembly which is inserted into the cannula 12 b. Thus, thetubular fabric 72 b is only exposed in the distal region 163 b distallyof the distal end 132 b of the cannula 12 b.

The embodiment of FIG. 33 differs from that of FIG. 29 in that thetubular fabric 72 b moving proximally is not disposed between theobturator shaft 18 b and the cannula 12 b. Rather, the proximally movingtubular fabric 72 a is disposed exteriorly of the shaft 18 b only in thedistal region 163 b. At the proximal end of this region 163 b, inproximity to the distal end 132 b of the cannula 12 b, the proximalmoving tubular fabric 72 b is directed through the windows 127 b and 130b back into the interior channel 83 b of the shaft 18 b.

Within the channel 83 b, the second end 76 b of the tubular fabric 72 bis attached to the ring 92 b. This calls for a special construction ofthe shaft 18 b and ring 92 b which is best described with reference tothe radial cross section view of FIG. 34.

In order to attach the second end 76 b of the tubular fabric 72 b (whichis disposed interiorly of the shaft 18 b) to the ring 92 b (which isdisposed exteriorly of the shaft 82 b), some structure is required toextend through the wall 81 b of the shaft 18 b. Initially, the shaft 18b can be formed with axial slots 165 which extend along the shaft 18 bbeneath the ring 92 b. These axial slots 165 are preferably equallyspaced around the circumference of the shaft 18 b. Spokes 167 integrallymolded with the ring 92 b, can be positioned in the slots 165 of theshaft 18 b to extend from regions exterior of the shaft 18 b to regionsinterior of the shaft 18 b. Within the channel 83 b, the second end 76 bof the tubular mesh can be attached to the spokes 167.

A similar embodiment of the invention is illustrated in FIG. 35 whereelements of structure similar to those previously discussed aredesignated by the same reference numerals followed by the lower caseletter “c”. In this case, the obturator shaft 18 c is formed at itsdistal end with a structure similar to that illustrated in FIG. 16.Thus, the shaft 18 c is formed with the converging planar surfaces 112 cand 114 c and the separate traction treads 101 c and 103 c, bestillustrated in FIG. 36. As previously discussed, this embodimentrequires both of the windows 127 c and 130 c, as well as the slot 116 c.This embodiment of the trocar system 10 c offers a further advantagethat the obturator 16 c can be used repeatedly with multiple cannulas 12c.

For those embodiments which offer this choice of repeated use, such asthe embodiments of FIGS. 29, 33 and 36, it may be desirable to providesome means for recycling the obturator 16 as illustrated in FIG. 37. Inthis case, a tension spring 170 is fixed at one end to the handle 21 cand at the other end to the first end 74 c of the tubular fabric 72 c.In operation, the ring 92 c is drawn proximally toward the handle 21 calong with the second end 76 c of the tubular fabric 72 c. This causesthe first end 74 c of the tubular fabric 72 c to move distallystretching the spring 170. The spring 170 is stretched even further(FIG. 38) as the ring 92 c is drawn proximally and the traction treads101 c and 103 c pass outwardly through the axial slot 116 c and inwardlythrough the windows 127 c and 130 c, respectively. When this operationis completed and the associated cannula 12 c is placed across theabdominal wall 25 c, the obturator 16 c can be withdrawn and the ring 92c released from its proximal-most position (FIG. 38). At this point, thebias of the spring 170 will pull the first ends 74 c of the tractiontreads 101 c, 103 c proximally. As the obturator 16 c is reset, thetreads 10 c, 103 c will pass outwardly through the windows 127 c, 130 c,respectively, and inwardly through the axial slot 116 c. This willenable the spring 170 to return to its normal, non-stretched state withthe ring 92 c disposed in its distal most position.

It can be appreciated that the spring 170 could be replaced with anybiasing means which mechanically, electrically or elastomericallyo, forexample, would bias the first end 74 c in the proximal direction.

With the foregoing description of these preferred embodiments, it can beappreciated that the structure forming the tubular fabric 72 as well asthe various traction treads 101, 103, 105 and 107, is of particularimportance to the present invention. This structure is preferably formedas a sheet material and is flexible and elongate with at least onetractive surface. These characteristics will be appreciated particularlyin those embodiments involving the traction treads 101 and 103 where thewidth of the treads remains generally constant. In these cases, thetread is able to maintain its width as it exits the distal slot 116 andenters the windows 127 and 130.

For those embodiments involving the distal exit hole 85, it may befurther desirable if the structure of the fabric is capable of radiallyexpanding and contracting. Particularly if the mesh is biased to thecontracted low-profile state, it will occupy less space within theinterior channel 83 and more easily feed through the exit hole 85. Abias to the contracted state will also facilitate removal of the fabric72 as illustrated in FIG. 28.

As noted, the fabric 72 preferably has a sheet configuration and can beeither woven or non-woven. It can be formed with filaments, which in thepreferred embodiment of FIG. 39, are divided into filament groups 170and 172 that extend in transverse directions. Thus the filaments in thegroup 170 may extend, in a normal state, perpendicular to the filamentsin the group 172, as illustrated in FIG. 39.

In order to facilitate the traction characteristics of the material 168,the filament groups 170 and 172 can be woven to form points ofintersection 174 where the filaments cross and spaces or interstices 176between the filaments. At the points of intersection, the fabric 72 willhave a thickness equal to the sum of the diameters of a single filamentin the group 170 and a single filament in the group 172. Between thepoints of intersection, the filaments in the groups 170 and 172 willprovide the fabric 72 with only a single thickness. In the interstices176 between the filaments of the groups 170 and 172, the material 168will have zero thickness. Thus, the woven configuration of even thissimple embodiment will provide the fabric 72 with three differentthicknesses greatly facilitating the traction between the material 168and the tissue associated with the abdominal wall 25 (FIG. 1).

Even those significant traction characteristics can be dramaticallyincreased with simple variations in the weave parameters. Consider forexample the effect of making the various filament groups 170, 172 withdifferent diameters. With an appropriate weave, this could add twoadditional levels of thickness to the fabric 72. Thus it is contemplatedthat any of the weaves known in the textile industry could providemultiple levels of thickness having dramatic effects on the traction ofthe fabric 72 relative to the tissue of the abdominal wall 25 (FIG. 1).

It should also be considered that any one of the filaments in the groups170 and 172 can be formed from a different material. Solid,non-resilient materials, such as monofilament, will tend to maintaintheir shape providing more of a mechanical traction to the tissue. Thefilaments could also be formed from fibrous materials, such as cotton,in which case traction would be further enhanced by capillary action.The filaments of the groups 170, 172 could also be individually variedin their diameters or thicknesses, or provided with a more tractivesurface, shape or coating.

In a preferred embodiment, the filaments forming the group 170 includemonofilaments which are alternated with cotton filaments. The samealternation of filament materials is applied to the filaments of thegroup 172. With even a simple weave of these filament groups 170 and172, significant variations in thickness occur due to the fixeddiameter-of the monofilanents and the variable diameter of the cottonfilaments. The resulting material 168 provides many differentthicknesses for high mechanical traction and additionally provides thecapillary action associated with fibrous cotton material.

Thermoplastic materials can also be used for the filaments in the groups170 and 172. These materials will permit the fabric 72 to be biased to acompacted state as illustrated in FIG. 40 and stretched to an expandedstate as illustrated in FIG. 41. This thermoplastic bias facilitatesmovement of the tubular fabric 72 between a low profile state interiorlyof the shaft 18 b, and an expanded high profile state exteriorly of theshaft 18 b. With a bias to the low profile state, the tubular fabric 72will automatically contract to achieve the advantages previouslydiscussed.

The fabric 72 can also be woven in a manner that the filaments of thegroup 170 are fixed to the filaments of the group 172 at each point ofintersection 174. This feature will tend to make the fabric 168 morerigid so that it does not tend to close down on the surface of thecannula 12 or shaft 18 as it is drawn proximally. The resulting fabric72 will also have less of a tendency to expand or contract. This maytend to produce pleats in the fabric 72 particularly where it emanatesfrom the axial hole 85 b. With reference to FIG. 42, it can be seen thatthese pleats 178 can provide the further advantage of texture variationsat the critical leading surface 87 of the obturator 16. This additionaltexture can even further enhance the traction with the tissue where theimportant parting of the tissue is taking place.

Alternatively, the filaments forming the group 170 and 172 can remaindisconnected at their points of intersection 74. This will enable thefilaments to move over each other enhancing their ability to expand andcontract. The characteristic of this weave is best illustrated in FIG.43 where the fabric 168 tends to maintain its cylindrical configurationas it passes through the axial hole 85 and moves from the low profilestate to the high profile state.

In a particular embodiment of the invention it may be desirable tocontrol the stretchability of the fabric 168 in different directions.For example, it may be desirable to facilitate radial expansion whileinhibiting axial expansion. The radial expansion might be desirable asit facilitates the transition of the tubular fabric 72 from the lowprofile state at the exit hole 85 b, to the high profile stateexteriorly of the cannula 12 or shaft 18. At the same time, it might bedesirable to inhibit expansion or contraction in the axial direction.Alternatives for providing different stretch characteristics indifferent directions are well known in the textile industry and includeformation of the fabric 72 with filaments of different material andshape as well as orientation of the filaments relative to the cut of thefabric 168.

A further embodiment of the invention is illustrated in FIG. 44 whereelements of structure similar to those previously discussed aredesignated with the same reference numeral followed by the lower caseletter “d.” In the side elevation view of FIG. 44, the obturator 16 d isillustrated with its wall 81 b extending along an axis 181 to form ablunt tip 183 and the exit hole 85 d. A needle 185 having a sharpconical tip 187 is supported within the interior channel 83 d to extendslightly through the axial hole 85 d. In this embodiment, the tubularmesh 82 d is disposed around the needle 185 and exits through the axialhole 85 d and proximally along the wall 81 d in the manner previouslydiscussed. The needle 185 can be fixed to the obturator 16 b, or can bemoveable distally, either manually or automatically, to facilitatepenetration of the wall 25.

With this construction, the needle 185 can provide a microscopicpuncture which precedes the fabric 72 d as it exits from the hole 85 d.This microscopic puncture can provide the initial cut 152 in the fascia141 and/or facilitate puncture of the peritoneum 145 (FIG. 22). Even inthis embodiment it is desirable that the parting forces represented bythe arrows 152 and 154 of FIG. 22 predominate over any cuttingassociated with the conical tip 187. This will ensure that the obturator16 progresses along the line of weakness 94 to achieve the advantagespreviously discussed with reference to FIG. 6.

An insertion apparatus 201 adapted for use with the trocar system 10 ofthe present invention is illustrated in FIG. 46. This particularembodiment of the trocar system 10 includes the obturator handle 21,valve housing 14, cannula 12 and ring 92 coupled to the tubular fabric72. The insertion apparatus 201 includes a frame 203 fixed to alongitudinal tray 205 that extends along an axis 206 to a distal radialwall 207. The frame 203 includes a palm handle 210 and finger handle 212which operate a ratchet mechanism 214 to move a plunger 216 and a distalengagement pad along the-tray 205.

In operation, the trocar system 10 is placed within the tray 205 andaligned axially with its cannula 12 extending through a hole 221 in thedistal wall 207. Importantly, the ring 92 is disposed on the proximalside of the wall 207.

Mechanical, electrical, or hydraulic operation of the handles 210, 212moves the plunger 218 axially distally bringing the engagement pad 217into contact with the handle 21 of the trocar system 10. Furtheroperation of the handles 210 and 212 operates the ratchet assembly 214to move the cannula 12 distally within the tray 205 of the insertionapparatus 201. With distal movement of the ring 92 inhibited by the wall207, the ring 92 moves proximally relative to the advancing cannula 12.This deploys the tubular fabric 72 and causes it to move proximallyrelative to the outer surface of the cannula 12.

Use of this insertion apparatus 201 can significantly aid in placementof the trocar system 10. It not only provides some mechanical advantageto the process but is also operable by a single hand of the user.

In a further embodiment of the invention illustrated in FIG. 47,elements of structure similar to those previously discussed aredesignated by the same reference numeral followed by the lower caseletter “D.” Thus, this embodiment includes the obturator 16 b with shaft18 b having the distal tip 78 b. In this embodiment, a pair of gears 230and 234 are rotatable on the shaft 18 b and disposed radially withrespect to each other. Teeth 234 and 236 on the circumference of thegears 230 and 232 extend beyond the distal tip 78 b and form the leadingsurface 87 b of the obturator 16 b. The teeth 234 and 236 mesh betweenthe gears 230 and 232 so that these gears turn in opposing directionsgenerating the parting forces illustrated by the arrows 152 b and 154 b.A pilot gear 138 can be used to rotate one of the gears 130, 132 whichin turn rotates the opposing gear 232 or 230 respectively. The pilotgear 238 can be rotated by any suitable mechanism, such as a belt 241receiving an applied force from the proximal end of the obturator 16 b.In this case it can be seen that the traction treads mentioned withrespect to previous embodiments take the form of the gear teeth 234 and236 which are axially continuous and produce the parting forces at theleading surface 187 b. An end view of this embodiment is illustrated inFIG. 48. A further embodiment of the invention is illustrated in theaxial cross section view of FIG. 49 and the associated end view of FIG.50, where elements of structure similar to those previously disclosedare designated by the same reference numeral followed by the lower caseletter “E.” Thus, the obturator 16 e includes a single gear 243 exposedat the distal tip 78 e. In this case, the idle gear 238 e is rotatableby the belt 241 e alternately clockwise and counter-clockwise. Thisoscillating movement is transferred to the gear 230 e causing its teeth234 e to move back and forth at the leading surface 87 e. Thisoscillating movement is illustrated by an arrow 245 in FIGS. 49 and 50.

Many alterations and modifications can be made to the foregoingpreferred embodiments without departing from the spirit and scope of theinvention. Therefore it must be understood that the illustratedembodiments have been set forth only by way of example, and should notbe taken as limiting the invention. For example, notwithstanding thefact that the claims set forth below recite certain elements andcombinations, it must be expressly understood that the inventionincludes other combinations of fewer, more or different elements, whichare not disclosed above even when not initially claimed in suchcombinations.

In addition, the words used in this specification to describe theinvention and its various embodiments are to be understood not only inthe sense of their commonly defined meanings, but also in the sense ofany special definitions used in this specification, which may extendbeyond the scope of the commonly defined meanings. Thus if an elementcan be understood in the context of this specification as including morethan one meaning, than its use in the claims must be understood as beinggeneric to all possible meanings supported by the specification and bythe word itself

The definitions of the words or elements of the following claims are,therefore, defined in the specification to include not only thecombination of the elements which are literally set forth, but allequivalent structure, material or method steps for performingsubstantially the same function, in substantially the same way, toobtain substantially the same way to obtain substantially the sameresult. In this sense it is therefore contemplated that an equivalentsubstitution of two or more elements may be made for any one of theelements in the claims below or that a single element may be substitutedfor two or more elements in a claim. Insubstantial changes from theclaimed subject matter, now known or later devised, are expresslycontemplated as being equivalently within the scope of the claims.Therefore, obvious substitutions now or later known to one with ordinaryskill in the art are deemed to be within the scope of the definedelements.

The claims are thus to be understood to include what is specificallyillustrated and described above, what is conceptually equivalent, whatcan be obviously substituted, and also what essentially incorporates theidea of the invention.

Many alterations and modifications can be made to the foregoingpreferred embodiments without departing from the spirit and scope of theinvention. Therefore it must be understood that the illustratedembodiments have been set forth only by way of example, and should notbe taken as limiting the invention. For example, notwithstanding thefact that the claims set forth below recite certain elements andcombinations, it must be expressly understood that the inventionincludes other.

1. A surgical instrument for parting tissue within an abdominal wallretaining internal organs, comprising: a shaft having an outer surfaceand a tip; a mesh sheath initially contacting the body tissue generallyat a point and extending proximally and stretching radially from thepoint along the outer surface of the shaft; the shaft being operable tocreate a distal force on the body tissue; the mesh sheath being biasedto a low profile state and stretchable to an expanded, high profilestate; the mesh sheath being operable to create a proximal force on thebody tissue; and the proximal force being greater than the distal forceto create a net proximal force on the abdominal wall tending to separatethe abdominal wall from the internal organs as the tissue is parted. 2.A surgical instrument, comprising: a shaft having a tubularconfiguration with an outer surface, an axial channel, and a distal tip;a flexible mesh sheath having a tubular configuration and extending fromthe axial channel of the shaft through the distal tip of the shaft; ahandle attached to the sheath exteriorly of the shaft, the handle beingmoveable proximally to withdraw the sheath from the channel and toprogressively invert the sheath at the tip of the shaft; and a cannula,wherein the shaft forms an obturator adapted for disposition within thecannula, the mesh sheath being biased to a low profile state andstretchable to an expanded, high profile state, and the sheath isdisposed to extend proximally outwardly of the obturator.
 3. Thesurgical instrument recited in claim 2, wherein when the shaft isdisposed within the cannula, the sheath is disposed to extend proximallyoutwardly of the obturator and the cannula.
 4. The surgical instrumentrecited in claim 2 wherein when the shaft is disposed within thecannula, the sheath is disposed to extend proximally between theobturator and the cannula.
 5. A surgical instrument, comprising: a shafthaving a tubular configuration with an outer surface, an axial channel,and a distal tip; a flexible sheath having a tubular configuration andextending from the axial channel of the shaft through the distal tip ofthe shaft; a handle attached to the sheath exteriorly of the shaft, thehandle being moveable proximally to withdraw the sheath from the channeland to progressively invert the sheath at the tip of the shaft; and acannula, wherein the shaft forms an obturator adapted for dispositionwithin the cannula, the shaft is disposed within the cannula, and thesheath is disposed to extend proximally outwardly of the obturatorbetween the obturator and the cannula.